I am a law school graduate. What I offer is mere information, not to be construed as forming an attorney client relationship.
Well, if you wuold like people on this board to help you, you need to be a bit more specific.
As it stands, if this is a genuine threat and there is an implication of falsehoods being spread about you or malicious actions taken simply to ruin your career, you have either or both a defamation action and an interference with livelihood or something like that action.
Your best bet is to think long and hard about what your situation really is and what it could become and then seek the advice of an employment labor law attorney in your state.